The present invention relates to an integrated circuit device cooling structure and, more particularly, to an integrated circuit device cooling structure which cools an integrated circuit device, which is packaged by flip chip bonding called an area bump method or in a ball grid array (BGA) package, with air by attaching a heat sink to it.
Conventionally, in an integrated circuit device cooling structure of this type, the integrated circuit device is mounted on a wiring substrate such that its lower surface faces the upper surface of the wiring substrate. A heat sink is attached to the upper surface of the integrated circuit device.
FIG. 6 shows a conventional integrated circuit device of this type. Referring to FIG. 6, a heat sink 26 is arranged on the upper surface of an integrated circuit device 21. The lower surface of the heat sink 26 is fixed to the upper surface of the integrated circuit device 21 so that it is thermally coupled to the integrated circuit device 21. Heat generated by the integrated circuit device 21 is transmitted to the heat sink 26 and is radiated in the air.
Solder bumps 22 used for inputting/outputting signals and connecting a power supply are formed on the lower surface of the integrated circuit device 21. The integrated circuit device 21 is not directly mounted on a wiring substrate 25 but is mounted on an interposer substrate 23 through the solder bumps 22. This is because the solder bumps 22 have a small pitch and the integrated circuit device 21 cannot be directly mounted on the wiring substrate 25.
Solder balls 24 are arranged on the lower surface of the interposer substrate 23. The solder balls 24 are arranged at such a pitch that they can be mounted on the wiring substrate 25. The interposer substrate 23 is mounted on the wiring substrate 25 through the solder balls 24.
The prior art described above cannot cope with an increase in power consumption that accompanies an increase in operation speed and integration degree of the integrated circuit device 21. To cope with an increase in power consumption of the integrated circuit device 21, the size of the heat sink 26 must be increased, but the cooling performance does not increase in proportion to an increase in size of the heat sink 26. To attach a large heat sink 26 to the integrated circuit device 21, the attaching structure must also be improved in accordance with the heat sink 26.